Sometimes we want to express loose relationships between destination guides and itineraries, travel topics, phrasebooks, geographic expeditions and region-specific policy pages (like Wikitravel:Manual of style for the US). The destination guide for a place and a part of that place, like California and Southern California, is a "tight" relationship, but the relationship between California and a travel topic like Off-road vehicles in California is loose.
This gives us the ability to concentrate on "core" travel guides for a general audience and still make space for related articles for more specific use.
For presentation, we have an area in the left-hand nav bar for related itineraries, travel topics, expeditions, region-specific policies and phrasebooks.
At some point in the future, the related articles section might be split up by article type (phrasebooks, itineraries, etc.).